gdb/psymtab.h

/* Public partial symbol table definitions.

   Copyright (C) 2009-2022 Free Software Foundation, Inc.

   This file is part of GDB.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

#ifndef PSYMTAB_H
#define PSYMTAB_H

#include "gdbsupport/gdb_obstack.h"
#include "symfile.h"
#include "gdbsupport/next-iterator.h"
#include "bcache.h"

struct partial_symbol;

/* Specialization of bcache to store partial symbols.  */

struct psymbol_bcache : public gdb::bcache
{
  /* Calculate a hash code for the given partial symbol.  The hash is
     calculated using the symbol's value, language, domain, class
     and name.  These are the values which are set by
     add_psymbol_to_bcache.  */
  unsigned long hash (const void *addr, int length) override;

  /* Returns true if the symbol LEFT equals the symbol RIGHT.
     For the comparison this function uses a symbols value,
     language, domain, class and name.  */
  int compare (const void *left, const void *right, int length) override;
};

/* An instance of this class manages the partial symbol tables and
   partial symbols for a given objfile.

   The core psymtab functions -- those in psymtab.c -- arrange for
   nearly all psymtab- and psymbol-related allocations to happen
   either in the psymtab_storage object (either on its obstack or in
   other memory managed by this class), or on the per-BFD object.  The
   only link from the psymtab storage object back to the objfile (or
   objfile_obstack) that is made by the core psymtab code is the
   compunit_symtab member in the standard_psymtab -- and a given
   symbol reader can avoid this by implementing its own subclasses of
   partial_symtab.

   However, it is up to each symbol reader to maintain this invariant
   in other ways, if it wants to reuse psymtabs across multiple
   objfiles.  The main issue here is ensuring that read_symtab_private
   does not point into objfile_obstack.  */

class psymtab_storage
{
public:
  psymtab_storage () = default;
  ~psymtab_storage ();

  DISABLE_COPY_AND_ASSIGN (psymtab_storage);

  /* Discard all partial symbol tables starting with "psymtabs" and
     proceeding until "to" has been discarded.  */

  void discard_psymtabs_to (struct partial_symtab *to)
  {
    while (psymtabs != to)
      discard_psymtab (psymtabs);
  }

  /* Discard the partial symbol table.  */

  void discard_psymtab (struct partial_symtab *pst);

  /* Return the obstack that is used for storage by this object.  */

  struct obstack *obstack ()
  {
    if (!m_obstack.has_value ())
      m_obstack.emplace ();
    return &*m_obstack;
  }

  /* Allocate storage for the "dependencies" field of a psymtab.
     NUMBER says how many dependencies there are.  */

  struct partial_symtab **allocate_dependencies (int number)
  {
    return OBSTACK_CALLOC (obstack (), number, struct partial_symtab *);
  }

  /* Install a psymtab on the psymtab list.  This transfers ownership
     of PST to this object.  */

  void install_psymtab (partial_symtab *pst);

  using partial_symtab_range = next_range<partial_symtab>;

  /* A range adapter that makes it possible to iterate over all
     psymtabs in one objfile.  */

  partial_symtab_range range ()
  {
    return partial_symtab_range (psymtabs);
  }


  /* Each objfile points to a linked list of partial symtabs derived from
     this file, one partial symtab structure for each compilation unit
     (source file).  */

  struct partial_symtab *psymtabs = nullptr;

  /* A byte cache where we can stash arbitrary "chunks" of bytes that
     will not change.  */

  psymbol_bcache psymbol_cache;

private:

  /* The obstack where allocations are made.  This is lazily allocated
     so that we don't waste memory when there are no psymtabs.  */

  gdb::optional<auto_obstack> m_obstack;
};

#endif /* PSYMTAB_H */